“I chose my opponent for September 14th and it’s Canelo Alvarez,” Mayweather said Wednesday night on Twitter. “I’m giving the fans what they want. It will be at the MGM Grand.”

Alvarez sent a tweet in Spanish announcing the fight.

The 36-year-old Mayweather is unbeaten in 44 fights, the last a unanimous 12-round decision over Robert Guerrero on May 4 at the MGM Grand in defense of his 147-pound title.

Alvarez is 42-0-1. The 22-year-old fighter unified the 154-pounds titles April 20 in San Antonio with a unanimous victory over Austin Trout.

The fight will be contested at 152 pounds and offers a rare bout between two unbeaten fighters in their primes.

“Floyd has said from Day 1 that he wants to give fans the best fight out there and here it is,” Mayweather’s co-manager, Leonard Ellerbe, told the AP. “We have the two biggest stars in the sport and they’re fighting each other Sept. 14.”

The bout will be the second in Mayweather’s six-fight, 30-month contract with Showtime that could pay him more than $200 million.